1. Field of the Invention
The present invention relates to a novel thermoplastic resin composition which is used in the production of a molded article by injection molding and extrusion molding.
2. Description of the Related Art
In general, a polyphenylene ether has excellent properties such as heat resistance, hot water resistance, dimensional stability, and mechanical and electrical properties, while it has some drawbacks such as poor moldability due to high melt viscosity, low chemical resistance and low heat impact resistance.
As a composition which improves the moldability by decreasing the melt viscosity while maintaining other good properties of the polyphenylene ether, there is known a composition comprising the polyphenylene ether and a polystyrene resin. However, the chemical resistance is not improved.
Since polyolefin is excellent in moldability, toughness, water resistance and chemical resistance, has a low specific gravity and is cheap, it is widely used as a raw material of various molded articles, a film or a sheet.
However, the polyolefin is insufficient in heat resistance, stiffness, impact resistance, coating properties or adhesion, or should be improved in such properties. This prevent new application of the polyolefin. In particular, improvement of the heat resistance and the impact resistance is highly desired.
In view of the above circumstances, it may be expected that a wide variety of new applications could be found if the polyphenylene ether and the polyolefin were compounded to give a resin composition having the good properties of the both polymers and improved moldability and impact resistance.
However, practically, the polyphenylene ether and the polyolefin have poor compatibility with each other even if they are compounded, so that, in a molded article produced by the injection molding, the polyphenylene ether and the polyolefin are phase separated, and the article has extremely poor appearance and deteriorated mechanical properties and cannot be used practically.
To improve the compatibility between the polyphenylene ether and a propylene polymer, for example, EP-A-329 423 discloses the use of a propylene polymer to which a styrene monomer is graft polymerized in combination with the polyphenylene ether.
EP-A-329 423 discloses that a composition having good heat resistance and mechanical properties is obtained by compounding the propylene polymer to which styrene or a mixture of styrene and a monomer copolymerizable with styrene is grafted or a rubber in the polyphenylene ether. Japanese Patent KOKAI Publication No. 173137/1990 discloses a resin composition comprising polyolefin having an amino group and a polyphenylene ether having a polar group.
Further, Japanese Patent KOKAI Publication No. 1489/1991 discloses a resin composition comprising a modified polyphenylene ether to which a mixture of a styrene monomer and an amino group-containing monomer is grafted and polypropylene having a functional group.
When one of the above resin compositions is used, a molded article is not necessarily satisfactory in impact resistance, heat resistance, moldability, elongation or chemical resistance. Therefore, in some applications, the use of such composition is difficult. In addition, the preparation of the composition itself is not necessarily easy, or the composition is expensive. Therefore, the market requires a cheap composition having improved properties.